BeagleBoard Consumption - Beagel Juice

Hi all,

I'm very keen on buying a beagle board xm for projects as i want to
step up my technology skills away from working with programs and
operating systems and into hardware side.

The beagle board boasts its low power consumption, but what is the
actual figure? I've heard it as low as 40mah after some modding.

Also i've noticed the beagle juice power pack. Here are its specs;

■ 4500 mAh battery
■ 5V output
■1.5A current delivery
■ Powers a BeagleBoard for at least 6.5 hrs

Other than being a tad expensive and bulky, i'd like to use a polymer
lithium battery - 6ah 3.7 volts

http://www.sparkfun.com/products/8484

I know that the volts are lacking, but is there any way to boost the
voltage? ( I have no experience in electricty at all, other than last
years high school lesson :smiley: )

There is also 6ah (6000 mah, i reckon) which from my understanding
will lengthen the battery life.

What will I need to make all this possible, and how much longer/
shorter can i possible get from this battery.

Thanks

Flemingjp

The power consumption depends totally on your application.

What is you maximum speed?
Are you using the DSP?
How long will it be running at the maximum speed?
What sort of display do you have?
Are you using the USB ports? If so, what is the load for each port? How much time will be spent with the ports in operation at full load?
Are you using the Ethernet port?
Are you using the camera port?
Is there anything connected to the expansion port?

As the Beaglejuice, it all depends on these issues as well. At 1.5A maximum, it could be a little underpowered. Or, it may be fine, again depending on your requirements based on your application.

I suggest you look a the application from these standpoints and try to determine the load based on the use cases you have. That will tell you the average current per hour and from there you can calculate the battery life based on the battery capacity.

Gerald

Hey thanks for that help. Im looking to use it as a pc. Probaly low
usb load that's all I know atm. In advanced im only 13, so please
don't throw terminology all at once. Again I have no experience with
hardware it this form.

Understood. Here is my suggestion. Get yourself a vol meter that can measure current. Hook that in series with the 5V power rail. Then, do what ever it is that you want to do. Read the current and that gives you an idea of how long it will last based on the current.

I don’t now if the BeagleJuice has ever been plugged into an xM version or not. What you might want to do is move to the BeagleBoard Rev C4. I know the BeagleJuice works on that. The folks at Liquidware should be able to help if you have issues, but at least you will be using something that you know will work together.

Gerald

James Fleming wrote:

Hi all,

I'm very keen on buying a beagle board xm for projects as i want to
step up my technology skills away from working with programs and
operating systems and into hardware side.

The beagle board boasts its low power consumption, but what is the
actual figure? I've heard it as low as 40mah after some modding.

Also i've noticed the beagle juice power pack. Here are its specs;

■ 4500 mAh battery
■ 5V output
■1.5A current delivery
■ Powers a BeagleBoard for at least 6.5 hrs

Other than being a tad expensive and bulky, i'd like to use a polymer
lithium battery - 6ah 3.7 volts

http://www.sparkfun.com/products/8484

I know that the volts are lacking,

beagle juice is not just a battery, but also circuitry
to provide 5V since that is what the beagle expects.

your LiPo battery is just a battery and needs the
same or similar circuitry added to power the beagle.

Ah, I understand a bit better, yet I want to create the smallest form
I can. Using, say 3-4 of the Li-po batteries would make it smaller and
thinner (probably theost crucial detail for my ideas) and hopefully
have a battery life same or greater than beagle juice.

I've done some rough estimates using calculators from the web. Only
using two varibles (batery ma, device consumption) gives a very crude
answer, yet reading forums I think there is much more to it, such as
resistance and discharge ect.

Did you download the BeagleBoard-xM System Reference Manual? If yes, turn to page 26. You should see Table 3 with the Electrical Specification. The third line is of interest to you:

      Min Typ Max Unit
Input Voltage DC 4.8 5 5.2 V

Some pages earlier the manual also says you need a regulated power supply. A battery is not regulated: Take a volt meter and measure your Li-Po battery. It will probably show much more than the advertised 3.7V, but much less if under load (i.e. when something like the beagleboard draws power) or if partly discharged.

So while we can't rule out from the specification that the beagleboard somewhat works even with 3.7V (wonders do happen in electronics ;-), it is highly unlikely. To get a reliable board, you usually should follow the specification.

Now you could connect two of your Li-Po batteries in series to create a battery with 6.8Volt and 6ah. You then need to add a low-drop voltage regulator (for example http://www.national.com/mpf/LP/LP3875.html#Overview although its max 7V input voltage is awfully close to the nominal 6.8 Volts of the two batteries) with a few capacitors and you would have 5V with 6 ah.

Be careful with the circuitry, mistakes can cost hardware, unlike software bugs :wink:

Holger Hellmuth wrote:

Now you could connect two of your Li-Po batteries in series to create a
battery with 6.8Volt and 6ah. You then need to add a low-drop voltage
regulator (for example
http://www.national.com/mpf/LP/LP3875.html#Overview although its max 7V
input voltage is awfully close to the nominal 6.8 Volts of the two
batteries) with a few capacitors and you would have 5V with 6 ah.

a fully charged LiIon is 4.2V, so 2 of them are 8.4V...

This was my intention in the first place, use two-four li-po batteries
in a circuit to provide around 7v and 6ah. Then add a regulator to
reduce this power, yet i don't know if it has been done. As for buying
a beagle board I probably buy a second hand beagle board (not the xm
version) as one wrong move and like holder said;

Be careful with the circuitry, mistakes can cost hardware, unlike
software bugs :wink:

Holger Hellmuth wrote:

Hi James,

I've spent quite a lot of time searching for good module and now we
are using this regulator from pololu to drive BeagleBoardXM from LiPo
batteries.

http://www.pololu.com/catalog/product/2110

We are using 3 Cells LiPo and it works very well with almost no
soldering required. The module will work with 2 or 4 Cells as well.
You, probably, won't need more than 3.5A. As far as I remember, the
board without USB devices need around 0.8 - 1.2 A, depending on
whether DSS is on or off. Each USB device could take 0.5A max, so you
can calculate yourself.

Obviously, you need to take care of charging yourself. Which is the
most complicated part with LiPo batteries :slight_smile:

Concerting board, I would recommend using XM board, as it has high
voltage protection, so, the chance of frying it is much lower,
actually. Normal beagle board doesn't have this protection.

Hope this helps,
Maksym Parkachov.
http://veter-project.blogspot.com/

You might want to take a look at an excellent project called ‘Beagleboard Extention’ launched by someone called Mike.
http://sourceforge.net/apps/mediawiki/beagleextension/index.php?title=DC_In_and_Battery_Charger

AFAIU, the schematic is not tested, so YMMV. If it does work out-of-the-box (i.e. after assembly), you’ve got yourself a complete backup power-management, battery management module.